Memory provides data storage for electronic systems. Flash memory is one type of memory, and has numerous uses in modern computers and devices. For instance, modern personal computers may have BIOS stored on a flash memory chip. As another example, it is becoming increasingly common for computers and other devices to utilize flash memory in solid state drives to replace conventional hard drives. As yet another example, flash memory is popular in wireless electronic devices because it enables manufacturers to support new communication protocols as they become standardized, and to provide the ability to remotely upgrade the devices for enhanced features.
NAND may be a basic architecture of integrated flash memory. A NAND cell unit comprises at least one selecting device coupled in series to a serial combination of memory cells (with the serial combination commonly being referred to as a NAND string). NAND architecture may be configured to comprise vertically-stacked memory cells, and such architecture may be referred to as three-dimensional NAND.
Three-dimensional NAND may have a vertical channel extending along the vertical-stacked memory cells of a NAND string, and the channel may extend to a region under the string (such region may be a source line, a conductive interconnect over another NAND deck, etc.). A problem that may be encountered with three-dimensional NAND is that a segment of the channel which joins with the region under the NAND string may have relatively high resistance as compared to other regions of the channel that extend along the NAND string (and that are gated by memory cells of the NAND string). The high resistance of such segment of the channel may degrade performance of three-dimensional NAND architecture.
It is desired to develop structures which alleviate the above-described problem associated with three-dimensional NAND architecture.